Pentax hd da 70mm f 2 4 limited vs pentax hd da 40mm f 2 8 limited?

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From Pentax HD DA 40mm f/2.8 Limited: Pentax HD DA 40mm f/2.8 Limited: A prime lens by Pentax for APS-C cameras, 40mm f/2.8. A pancake lens that keeps the camera small. Specs - Maker: Pentax - Focal length: 40mm (prime) - Maximum aperture: f/2.8 - Made for: APS-C sensors - Mounts: Pentax K - Stabilised: no - Autofocus: yes What it frames like - On APS-C (Pentax K): like 60mm on full frame; f/2.8 gives about the depth of field of f/4.2 there. ...

From Pentax HD DA 70mm f/2.4 Limited: Pentax HD DA 70mm f/2.4 Limited: A prime lens by Pentax for APS-C cameras, 70mm f/2.4. Specs - Maker: Pentax - Focal length: 70mm (prime) - Maximum aperture: f/2.4 - Made for: APS-C sensors - Mounts: Pentax K - Stabilised: no - Autofocus: yes What it frames like - On APS-C (Pentax K): like 105mm on full frame; f/2.4 gives about the depth of field of f/3.6 there. - On the larger-sensor bodies of Pentax K: ...

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